Cardboard or paperboard boxes are useful for shipping and storing goods or products. It is common to form such a box from a single blank. Typically, the blank has four main panels for forming the top, bottom, front and back of the box, and has side panels extending from the main panels for forming the sides of the box. The adjacent flaps are separated by wide gaps (or slots) for ease of production and assembly. Tear lines may be provided on the blank so that a portion of the box may be removed along the tear lines to convert a packaging box to a display box. Such blanks and boxes are disclosed in, for example, WO 01/87721 to Maus, and U.S. Pat. No. 7,784,676 to Borek et al. In some situations, the known blanks and boxes such as those disclosed in the above references are adequate, but in some situations, they are either not suitable, or do not provide sufficient box strength to resist deformation under an applied pressure during use.